Heart Failure Still a Problem but Less of a Burden on Acute MI Patients

Heart failure has become a less
frequent complicating factor for acute MI over time and related mortality has
declined, but it remains associated with worse short- and long-term outcomes.
The findings, from a Swedish registry, were published in the March 2015 issue
of JACC: Heart Failure.

Although the gains are encouraging, the continued negative
impact on outcomes “can’t be ignored, warranting early identification of
patients with [heart failure] for initiation of effective treatment strategies
and closer follow-up to prevent adverse outcomes,” Liyew Desta, MD, of the Danderyd
University Hospital (Stockholm, Sweden), told TCTMD in an email.

“Simple clinical findings, such
as pulmonary rales (Killip classification), have a huge role in the risk
stratification of patients who could be targets of specific therapies and
follow-up strategies, underscoring the importance of meticulous evaluation,” he
added.

Dr. Desta and
colleagues looked at data from the SWEDEHEART/RIKS-HIA registry on
199,851 acute MI patients admitted to Swedish coronary care units from 1996 to
2008. During the study period, there were increases in mean age; the proportion
of women; and rates of diabetes, current smoking, and hypertension and
decreases in rates of prior histories of acute MI and congestive heart failure.

Heart failure—defined as the presence of pulmonary rales and use of
continuous positive airway pressure (CPAP) or IV diuretics or inotropic drugs,
with severity assessed by the Killip classification—complicated fewer
admissions over time, with the rate falling from 46% in 1996-1997 to 28% in
2008 (P < .001). The declines were
evident across age groups, with greater reductions seen in patients with STEMI
and left bundle branch block than in those with NSTEMI. There were
corresponding drops in use of CPAP and IV diuretics and inotropic drugs.

The proportion of heart failure patients
with an ejection fraction of 50% or higher (normal) increased while that of
patients with an ejection fraction under 40% decreased.

Over time, use of evidence-based
therapies improved, with increasing use of PCI and various discharge
medications, including aspirin, clopidogrel, beta-blockers, statins, and ACE
inhibitors or angiotensin II receptor blockers.

All of these shifts translated
into better outcomes for patients who had heart failure as the study
progressed. Mortality rates dropped in the hospital (19% to 13%), at 30 days
(23% to 17%), and at 1 year (36% to 31%; P
< .001 for trend). After multivariate adjustment, the odds of 1-year
mortality declined among patients with clinical heart failure over time (OR per
2 calendar years 0.93; 95% CI 0.92-0.94).

Nevertheless, the presence of
heart failure in and of itself put patients at twice the risk of mortality
(adjusted HR 2.09; 95% CI 2.06-2.13).

Better Treatment Likely Behind Heart Failure Decline

One possible reason that heart
failure is seen less frequently in patients with acute MI is that smaller infarcts
are being detected, according to the authors.

An acute MI diagnosis based on “increasingly sensitive serial biomarkers has substantially increased
the detection of [acute MI] cases, counteracting the actual declining rates of [the
condition],” they write. “Smaller [acute MIs] that could have been missed with
previous criteria are detected with the new criteria, which in turn could
contribute to a reduced risk for subsequent [heart failure], as [heart failure]
is related to infarct size.”

They note,
however, that the reduction in heart failure did not change dramatically when
the more sensitive definition of acute MI was introduced.

“We rather saw a
smooth progressive decline, suggesting other explanations, such as more
frequent use of effective evidence-based treatments and changes in the burden
of risk factors,” they write. “The greater decrease of [heart failure] observed
in patients with STEMIs compared with those with NSTEMIs also argues against
the suggestion that an overall decline in [heart failure] incidence is merely a
reflection of the detection of smaller infarcts.”

Clyde W. Yancy,
MD, of Northwestern University Feinberg School of Medicine, agreed in a
telephone interview with TCTMD.

“Overall, I think it would be pretty hard to not recognize
that there have been some real gains in the care of patients with acute MI, and
in addition to a lesser risk of death, a shorter length of stay, and a better
quality of life—because we’ve preserved muscle—there’s less heart failure,” he
said, noting that the findings from Sweden are likely applicable to other
developed countries, including the United States. “Everything that we’ve been
doing up until now has worked.”

He said that the situation is probably even better now
than in 2008 but added that heart failure continues to be a problem in patients
with acute MI. “So it speaks to prompt early therapy for ACS and then for heart
failure… [and] it shows you that we can prevent a disease that has still
significant consequences. Maybe the best way to do that is to continue to focus
even further upstream and prevent the initial event from occurring,” Dr. Yancy
suggested.

Justin A. Ezekowitz, MBBCh, MSc, of the University of
Alberta (Edmonton, Canada), echoed the belief that general improvements in ACS
care—including better ambulance systems, earlier identification of symptoms,
and earlier use of thrombolysis or PCI—were the main reasons for the observed
trends. “Really the implications are that with a better system, people will do
better,” he told TCTMD in a telephone interview.

He said it is important for clinicians to recognize the
signs and symptoms of heart failure during an MI. Heart failure is “a very
important marker for somebody who’s at higher risk than those who do not have
that, so clinicians should pay attention to that and act accordingly,” Dr.
Ezekowitz said. “Sometimes that’s going to be [using] newer or different
therapies and implementing other guideline-based medical therapy. And sometimes
it’s going to mean more or greater surveillance in hospital but also
importantly, after hospital; those patients are going to be the ones where you
really want to do earlier and much closer surveillance after discharge.”

Study Limitations

The authors acknowledge that the registry data could not be used to
distinguish between patients who had clinical heart failure prior to admission
and those who developed it during the hospital stay. Also, there was no information
on aldosterone antagonist use.

An additional limitation, note Anuradha
Lala, MD, and Judith S. Hochman, MD, of New York University School of Medicine
(New York, NY), in an accompanying editorial, is that “the definition of [heart failure] can be complicated, and cases may have been missed by not assessing other commonly used signs
reflecting congestion, such as
elevated jugular venous pressure,
orthopnea, and natriuretic peptide levels.”

Even so, the study shows that “the continued use of the Killip
classification helps identify a high-risk group for whom specific therapies need
to be targeted,” the editorialists say. “Patients with [heart failure] symptoms
after MI (ie, Killip class II or greater) likely require triage to a higher
level of care while in the hospital, meticulous attention to guideline-directed
medical therapy, and closer postdischarge follow-up to prevent adverse
outcomes.”

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